Error 31 means that Windows can't load the 3g modem driver. Are you running Windows 7 64-bit? What is the model number of the hauwei modem? Please be aware that there might not be a hauwei modem driver available for Windows 7...

I have a similar issue in my laptop. I am running windows 7 ultimate 32 bit version and using Huawei UMG1831 modem. The software used to connect to 3G network is mobile partner which comes bundled with the modem. It works absolutely fine but if i try to use standard windows dialer or any 3rd part dialer app like MDMA or reconnect or CiDial, i get the error 31 and same message as OP